There is a plurality of gas supply on the market right now, for example, according to the difference of heating value, there are the propane gas, the natural gas and the like, correspondingly the gas can be divided into the propane gas, the natural gas and the like as well, and there is a gas appliance integrated with a high-heating value gas igniting end and a low-heating value gas igniting end, and the two igniting ends are respectively connected with a corresponding igniting gas flow branch, therefore, not only can a high-heating value gas resource be connected but also a low-heating value gas resource can be connected, however, due to the difference of the heating value of the gas, the aperture of a gas nozzle for the main burner using the low-heating value gas is larger than that of the gas appliance using the high-heating value gas, thus when the low-heating value gas (such as the natural gas) nozzle induces the high-heating value gas (such as the propane gas) by mistake, the fire generated by the gas appliance is too high to be dangerous.